US3701922A

US3701922A - Electron beam line scanner with transverse binary control

Info

Publication number: US3701922A
Application number: US68326A
Authority: US
Inventors: Richard A Honzik
Original assignee: Northrop Grumman Corp
Current assignee: Northrop Grumman Corp; Northrop Grumman Systems Corp
Priority date: 1970-08-31
Filing date: 1970-08-31
Publication date: 1972-10-31
Anticipated expiration: 1989-10-31
Also published as: DE2139867A1; GB1302315A; FR2107082A5; JPS53266B1; NL7111496A; CA943260A

Abstract

A pair of dielectric plates have control electrodes formed on oppositely positioned broad surfaces thereof, there being an evacuated narrow space formed between such surfaces to provide paths for an electron beam between a cathode and a target. Such surfaces have conductive control electrodes formed thereon, the electrodes on one of the plates including paired electrodes arranged in a coded finger pattern defining electron beam channels between the cathode and target. The electrodes encompass substantially all of the plate surface area between which the channels are formed. Binary control signals are utilized to apply potentials to preselected ones of said electrodes to create transverse electric fields in the channels bounded thereby, thereby aborting the electron beam in such channels. The beam is in this manner permitted to pass through channels of the scanner in which there are no transverse fields so as to excite the target portions located by these channels.

Description

United States Patent [451 0ct.3l, 1972 Honzik [54] ELECTRON BEAM LINE SCANNER WITH TRANSVERSE BINARY CONTROL [72] Inventor: Richard A. Honzik, La Palma, Calif.

' [7 3] Assignee: Northrop Corporation, Beverly Hills, Calif.

[22] Filed: Aug. 31, 1970 [21] Appl. No.: 68,326

[52] US. Cl. ..315/10, 315/13, 313/83 [51] Int. Cl .1101] 31/26 [58] Field of Search ..315/10, 12, 13; 313/69, 76,

[56] References Cited UNITED STATES PATENTS 3,176,184 3/1965 Hopkins ..315/13 R 3,331,985 7/1967 Hamann ..315/13 R 3,406,273 10/1968 Holland ..313/76 X 3,408,532 10/1968 Hultberg et al ..315/12 3,483,422 12/1969 Novotny ..315/12 3,539,719 11/1970 Requa et a1 ..315/13 R 3,560,963 2/1971 Trilling ..313/76 3,600,627 8/1971 Goede ..315/13 R Primary ExaminerCarl D. Quarforth Assistant Examiner-P. A. Nelson Attorney-Sokolski & Wohlgemuth and W. M. Graham [5 7] ABSTRACT A pair of dielectric plates have control electrodes formed on oppositely positioned broad surfaces thereof, there being an evacuated narrow space formed between such surfaces to provide paths for an electron beam between a cathode and a target. Such surfaces have conductive control electrodes formed thereon, the electrodes on one of the plates including paired electrodes arranged in a coded finger pattern defining electron beam channels between the cathode and target. The electrodes encompass substantially all of the plate surface area between which the channels are formed. Binary control signals are utilized to apply potentials to preselected ones of said electrodes to create transverse electric fields in the channels bounded thereby, thereby aborting the electron beam in such channels. The beam is in this manner permitted to pass through channels of the scanner in which there are no transverse fields so as to excite the target portions located by these channels.

20 Claims, 6 Drawing Figures -u I PATENTED BT31 I972 3.701.922

SHEET 1 BF 2 FIG. 2

FIG. 3

Ian/ash I ems I Bmsh I BIAS h ADDRESSING CONTROL |wncH [swncH swrrcH lswrrcu B E A M 44

35a

35b 36G 36b 37! 37b 38a 38b 42 RICHARD A. HGJZIK 15$ 5& 55 i i 5 30 soKoLsm a WOHLGEMUTH PATENTEDncm m2 3.701.922

sum 2 or 2 FIG. 4

50 5| 52 53 55A ADDRESSING |B|As I BIAS I Hams Yams] CONTROL J 43 [SWITCH [swnu k [SWITCHM [SWITCHIJ BEAM FIG'G INVENTOR RICHARD A. HONZIK QDKOLSKI 8| WOHLGEMUTH ATTORNEYS ELECTRON BEAM LINE SCANNER WITH TRANSVERSE BINARY CONTROL This invention relates to electron beam line scanners and more particularly to such a scanner utilizing a pair of oppositely positioned plates which have coded electrodes thereon for effecting the scanning of an electron beam between a cathode and a target in response to a digital control signal.

In US. patent application Ser. No. 755,276, filed Aug. 26, i968, and assigned to Northrop Corporation, the assignee of the present application, an electron beam line scanner with dynode plates having thin conductive zigzag control strips thereon is described, in which potentials are applied between oppositely oriented strips to provide the scanning operation. In this device, a broad surface of each of the oppositely positioned control dynode plates is coated with a secondary emissive resistive material. The thin conductive strips are arranged on the plates over the secondary emissive material in a binary coded zigzag pattern, so as to define electron beam channels between the cathode and target. The plates are aligned with each other so that the zigzag patterns of the strips of one plate are in phase opposition with the zigzag patterns of the other. Binary switching control circuitry is utilized to selectively provide potentials, transverse to the direction of the electron beam, between the oppositely positioned strip elements in a manner such as to block the passage of electrons between the cathode and target in all but one selected electron beam channel at a time, the transverse electric fields effectively aborting the electron beam in the channels where they are applied. The device of this invention, as in the device of the aforementioned application, utilizes transverse electric fields applied to coded conductive elements for controlling the beam of an electron beam line scanner. However, it differs from the prior device in that no secondary emissive or resistive surfaces are required utilized. Rather, paired conductive control electrodes are utilized which encompass substantially all of the plate area between which the channels are formed. This greatly simplifies and lowers the cost of fabrication. Further, in the device of this invention, simple patterns which are relatively easy to form are utilized for the control electrodes for channeling the beam between the cathode and target.

The device of this invention has the advantage over the aforementioned device of easy alignment between the top and bottom plates in view of the fact that all of the coded information defining the channels may be on a single plate. Further, the need for having coded electrode patterns on only one of the plates makes for greater simplicity and economy of fabrication.

It is therefore the principal object of this invention to provide an improved electron beam line scanner utilizing transverse voltage control which is simpler and more economical to fabricate than prior devices of this type.

Other objects of this invention will become apparent as the description proceeds in connection with the accompanying drawings, of which:

FIG. 1 is a perspective view illustrating the general configuration of one embodiment of the invention,

FIG. 2 is an exploded view illustrating the embodiment shown in FIG. 1,

FIG. 3 is a schematic drawing illustrating control circuitry for the embodiment of FIGS. 1 and 2,

FIG. 4 is a schematic drawing illustrating a noncoded control plate of a second embodiment of the invention,

FIG. 5 is a schematic drawing illustrating control circuitry for the embodiment of FIG. 4, and

FIG. 6 is a perspective view of the control plates of a third embodiment of the invention.

Briefly described, the device of the invention comprises a pair of non-conductive plate members which are held with their broad surfaces opposite each other in close proximity so as to enable the formation of a plurality of electron beam channels between a cathode and a target which are positioned along opposite edges of the plate members. Means are provided to establish and maintain a vacuum tight condition in the space between the plate members. Means are further provided to accelerate electrons from the cathode towards the target. Formed on the broad surface of one of the plate members are a plurality of parallel rows of sets of paired electrodes, these electrodes being arranged in a coded finger pattern which defines a plurality of electron beam channels running between the cathode and the target. The fingers of each electrode pair are interdigitated with each other. Non-coded electrode means is formed on the opposing surface of the other of the plate members. The electrodes cover substantially all of the surface area of the plate members between which the channels are formed. Binary control means are provided to selectively apply potentials to the electrodes in a manner such that there is a transverse electric field placed across a portion of the channels to be kept inactive, the channels with no transverse electric field thereacross being activated. In this manner, the beam can be directed to any desired portion of the target in response to the binary control signals.

Referring now to FIGS. 1 and 2, one embodiment of the invention is illustrated. Plate members 11 and 12, which are preferably of a dielectric material such as glass or a suitable ceramic, are positioned with their broad surfaces opposite each other, a narrow slot 14 being formed between said surfaces. Plates 11 and 12 each have an

end plate

17 and 18 respectively attached thereto, these end plates extending beyond the broad surfaces of their associated plate members so as to separate the plates to form slot 14. In the assembled position, as shown in FIG. 1, the edge portion 170 of plate 17 abuts against the surface of plate 12 while the edge portion 18a of plate 18 abuts against the surface of plate 11.

End plates

17 and 18 are fabricated of a dielectric material which may be similar to that of the control plates and may be attached to the ends of the control plate by any suitable means such as cementing.

A cathode member 22 is positioned along one of the ends 11c and of plates 11 and 12 respectively, in overlapping relationship so as to provide a source of electrons along slot 14. The cathode member is separated from the plates by

insulator strips

26 and 27 placed therebetween. Cathode 22 may be of the thermionic type or may be a cold cathode of the radioactive or field emission type. Positioned along the end portions 11a and 12a of the control plates is target member 21 which is thus located opposite cathode 22 with the slot 14 located between the control plates and extending between the cathode and target members. The control plate and target members are separated from each other by means of

insulator strips

28 and 29 located therebetween. Target 21 may be coated with a phosphorescent material capable of providing a luruinous display with the impingement of electrons thereon or may be a memory plate or the like for collecting or storing electrical charge in accordance with the incidence of the electron beam thereon.

The assembled unit is maintained in a vacuum environment within evacuated casing 25.

Control plate 12 has a single electrode 30 on the broad surface thereof. This electrode covers the entire surface of control plate 12 and may be of a highly conductive material such as gold, copper or aluminum which may be placed on the surface by suitable means such as vacuum deposition. The end surfaces 12a and 120 are also preferably covered with conductive material. This plate may be entirely of a conductive material rather than comprising a dielectric substrate with a conductive electrode on a surface thereof.

Control plate 11 has a plurality of sets of coded electrodes 35a38a; 35b38b thereon. These electrodes are of a highly conductive material such as gold, copper, or aluminum. Electrodes 35a-38a; 35b-38b of control plate 11 as shown in FIG. 2 are arranged in a binary Gray code, electrodes 35a-38a each being paired in interdigitated relationship with a corresponding one of electrodes 35b-38b. Straight binary coding could also be utilized or other type of coding to an order other than binary. Each electrode is electrically insulated from each other electrode and is connected to appropriate switching circuitry as to be explained in connection with FIG. 3. Also on the surface of plate 11 are accelerator electrode 44 and modulator electrode 42 These electrodes are of a highly conductive material and are in the form of strips running along the opposite edges of the plate.

Electrodes

42 and 44 preferably have contiguous portions 420 and 440 which cover the plate end portions 11a and 110 respectively, this tending to minimize the possibility of charge build up in these areas which might adversely affect performance.

The integrated assembled unit thus comprises an electron emitting cathode 22 and an electron responsive target 21 between which are sandwiched a plurality of coded finger pattern electrodes for controlling the scanning of an electron beam between the cathode and target in response to digital control signals. The electron beam is effectively aborted by placing a transverse potential between electrode 30 and preselected ones of electrodes 35a-38a; 35b-38b, the electron beam passing through to the target in the channels formed by the finger pattern electrodes which have no transverse potentials thereacross.

Referring now to FIG. 3, the operation of the transverse control utilized to implement the scanning operation is schematically illustrated. Power source 40 has its negative terminal connected to cathode 22 and its positive terminal connected to ground.

Electrodes

30 and 44 and each of switches 45-48 which may comprise suitable electronic switching circuits such as flip-flops also are grounded. Power source 41 is connected between ground and target 21 to provide a positive potential on the target with respect to ground. Thus, an electric field is established accelerating electrons from cathode 22 towards target 21. Power source 40 establishes a relatively high potential between the cathode and the electrodes (in an operative embodiment of the order of 1,000 volts). Connected respectively to each of switches 4548 is a separate bias voltage source 50-53.

Each of the switches 4548 is selectively controlled in response to control signals from addressing control 55. One of the outputs of each of switches 4548 is connected to an associated one of electrodes 35a-38a while the other output of each of the switches is connected to an associated one of electrodes 35b-38b. The switching circuits may comprise flip-flops which are arranged so that the conducting stages thereof each feed through to their associated electrodes ground potential while the non-conducting stages are simultaneously feeding the voltage of appropriate ones of bias sources 50-53 to their associated electrodes. Thus, it can be seen that in response to addressing control 55, potentials can be selectively established on each one of electrodes 35a-38a, 35b-38b, to provide a potential difference between certain of these electrodes and electrode 30 and no potential difference between others of these electrodes and electrode 30. The resulting electron beam may be intensity modulated by means of a modulation signal fed to modulator electrode 42 from beam modulator 43.

For illustrative purposes, each of the outputs of switches 4548 connected to electrodes 35b-38b are indicated by a plus sign in FIG. 3 to provide a positive potential to each of these electrodes with respect to ground. A negative potential could be used as well. This potential represents that supplied by each of voltage bias sources 50-53. At the same time electrodes 35a-38a are receiving ground potential, the same potential as that on electrode 30. Under such conditions, a transverse electric field is created between electrode 30 and certain electrodes of plate 1 l in all of the channels defined by the finger pattern electrodes except that to the far left. It is to be noted at this point that for the electrode pattern of plate 1 1 shown in FIG. 2, eight channels are defined, these being delineated by each of the interdigitated fingers of

electrodes

38a and 38b. For the illustrative example, an electron beam as indicated by dotted line will pass from the cathode to the target, electron flow being aborted in all of the other channels by virtue of there being a transverse potential in some portion of each of these channels. It can readily be seen that by selectively actuating switches 4548 in various manners that the beam can be made to pass through any of the channels to provide either a regular or random scan. It is also to be noted that more than one of the channels can be energized at a time such that plural beams are provided. Such type of plural beam control requires separate independent switching control for each of the electrodes of plate 1 l, to enable independent control of the potentials to the individual electrodes of each pair.

Electrodes

38a and 38b provide filtering action to minimize the appearance of ghost signals at the target. Such filtering is utilized because it has been found that such ghosting may occur in channels where there is only a single electrode providing a transverse potential. The

filter electrodes

38a and 38b are appropriately energized to assure that each of the tumed off channels has at least two serially positioned elec trodes therein for providing a transverse field, so as to insure that the channels to be de-activated are successfully cut off with no significant number of electrons passing through them to the target.

In an operative embodiment of the invention, the accelerating potential provided by power source 40 is on the order of 1,000 volts. Transverse switching potentials on the order of only -15 volts are utilized when the electrodes of plate 11 have a width, w, which is 10 times the separation 1 between electrode and the electrodes of plate 11. The switching potential requirements, it has been found, are a function of this width to separation ratio, the magnitude of the required switching potential varying inversely therewith.

While the embodiment of FIGS. 13 has been shown for only eight channels, it should be immediately apparent that the number of such channels can be increased to any number desired by utilizing a greater number of control electrodes on plate 1 1 so as to define such additional channels.

It is to be noted that in the embodiment of FIGS. 1-3, the beam accelerating potential is applied between the cathode and the control electrodes. These electrodes could therefore in certain embodiments procide the dual functions of beam acceleration and control,

' thereby permitting the elimination of accelerator electrode 44.

Referring now to FIGS. 4 and 5, one of the plate members and the control circuitry of a second embodiment of the invention is respectively illustrated. In this embodiment, a potential gradient is established between the cathode and target by segmenting the electrode means on plate 12 into a plurality of separate electrodes and applying successively higher potentials to these electrode segments and the oppositely positioned electrodes of plate 11. This potential gradient aids in accelerating the electron beam. Otherwise the remaining components and operation are the same as for the first embodiment.

As can be seen in FIG. 4, plate 12 has a plurality of separate conductive electrodes 30a-30f thereon, these electrodes being electrically insulated from each other and, except for these insulating separation portions, covering substantially the entire surface of the plate. Electrodes 30b-30e are each positioned opposite an associated pair of electrodes a, 35b-38a, 38b of plate 11.

Electrodes

30a and 30f run

opposite electrodes

44 and 42 respectively.

Electrodes

30a and 30f, as for the embodiment shown in FIG. 2, also have contiguous portions (not shown) which cover the end portions 12a and 120 of the plate.

The potential gradient is established by means of voltage divider 65 which is connected across power source 49. The positive temiinal of power source 49 is connected to ground, while the negative terminal is connected to the

acceleration electrodes

30a and 44. Taps 65b-65e of voltage divider 65 are connected to electrodes 30b-30e and switches -48 respectively. Power source 41 is connected to target 21 to provide an electron accelerating potential thereto. Thus, each one of these electrodes and the switch associated with the oppositely positioned electrode on the other plate receives a potential which is increasingly higher as we go from the cathode to target. The switches 45-48 operate as in the first embodiment in response to addressing control 55 to alternatively connect to their associated electrodes either the potential fed thereto from divider 65 or this potential plus (or minus) the bias potential supplied thereto from bias sources 5053.

As for the first embodiment, in the channels wherein oppositely positioned electrodes have a potential difference established therebetween so as to create a transverse electric field, the electron beam is aborted, while in those channels where no such transverse field is created, the electron beam is permitted to pass through to the target.

The potential gradient between successive ones of electrodes 30a-30f may be of the order of 25-50 volts where the other parameters are substantially the same as those indicated for the embodiment of FIGS. 1-3.

Referring now to FIG. 6, the control plates of another embodiment of the device of the invention are illustrated. This embodiment differs from the previous embodiment in that grooves are provided in control plate 12 to define electron beam channels. Otherwise, the device is similar to the previous embodiments described. Control plate 12, which as for the previous embodiments, may be of a dielectric material such as glass or suitable ceramic, has a plurality of grooves formed in the broad surface thereof opposite to the electroded surface of control plate 11. These grooves are of a diameter such that they correspond and overlie each of the electron beam channels formed by the binary coded electrode pattern on the opposite surface of control plate 11, this pattern being the same as that shown in FIG. 2. Grooves 70 have electrodes 72 of a highly conductive material such as gold, copper, or aluminum, deposited therein. The electrodes 72 stop just short of the edges of the grooves so that there are insulating lands 74 formed between the grooves so as to avoid electrical contact between the electrodes of control plate 12 and those of control plate 11. The control plates illustrated in FIG. 6 are incorporated with the remaining structure and operated in response to control signals in the same manner described in connection with the embodiment of FIGS. 1-3. v

It is to be noted that, if so desired, the grooved portions 70 can alternatively be formed in the surface of control plate 11 or in the opposing surfaces of both plates to form cylindrical channels. The electrodes 72 of control plate 12 are connected together so that they all are maintained at the same potential by suitable interconnection means (not shown). The utilization of grooved defined channels, as illustrated in FIG. 6, in certain instances tends to provide better isolation between the individual channels, thus minimizing beam straying from one channel to another.

It is to be noted, that it is possible to fabricate the device of the invention with interdigitated coded finger pattern electrodes distributed between plates 11 and 12 rather than having all of the coded electrodes on one plate and all of the non-coded electrodes on the other. Distributing the electrodes in this fashion, however, makes it necessary to accurately laterally align the plates with each other to properly form the channels, which complicates the assembly of the device especially where a great number of channels are involved.

This invention thus provides an improved line scanner utilizing transverse control which is simpler and more economical to fabricate than prior art devices, in which secondary emitting dynodes are no longer required.

While the device of the invention has been described and illustrated in detail, it is clearly to be understood 'that this is intended by way of illustration and example only and is not to be taken by way of limitation, the scope and spirit of this invention being limited only by the terms of the following claims.

I claim:

1. In an electron beam line scanner, an electron source, a target and means for accelerating the flow of electrons between said electron source and target to form an electron beam therebetween, the improvement including means for causing said beam to scan said target in response to a digital addressing signal, comprismg:

a pair of plate members,

said plate members being positioned between the electron source and target with one of each of their broad surfaces opposite each other, said beam passing between said surfaces on a path substantially parallel thereto,

control electrode means on each of said opposite broad surfaces, said electrode means being positioned opposite each other,

said control electrode means comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels running between the cathode and target, the finger pattern portions of the electrodes of each of said sets of electrodes being interdigitated with each other, and noncoded electrode means positioned opposite each of said sets of paired electrodes, and

means for applying potentials between pre-selected ones of said finger pattern electrodes and said noncoded electrode means to provide transverse electric fields across selected ones of said channels, thereby preventing the flow of electrons in said selected channels, the electron flow being permitted in those channels having no transverse electric fields thereacross.

2. The scanner of claim 1 wherein said paired finger pattern electrodes are all arranged in successive rows on one of said plate members with the non-coded electrode means being on the other of said plate members opposite said paired electrodes.

3. The scanner of claim 1 wherein said paired coded finger pattern electrodes and said non-coded electrode means cover substantially all of surface area of the plate members between which said electron channels are formed.

4. The scanner of claim 2 wherein said non-coded electrode means comprises a single electrode covering substantially all of the broad surface area of the other of said plate members.

5. The scanner of claim 2 wherein said non-coded electrode means comprises a plurality of separate electrodes arranged in rows opposite said paired electrodes and means for applying successively higher potentials to the opposite electrodes in going from the cathode to the target.

6. The scanner of Claim 1 wherein said means for accelerating the flow of electrons comprises an accelerator electrode positioned between said cathode and said control electrode means and means for applying an accelerating potential to said accelerator electrode.

7. The scanner of claim 1 and further including modulator electrode means interposed between said electron source and said target and means for supplying a signal to said modulator electrode means for modulating said beam.

8. A electron beam line scanner comprising:

a pair of plate members,

control electrode means on one surface of each of said plate members,

means for positioning said plate members with the electrode means of one in opposing relationship and in close proximity to the electrode means of the other,

the electrode means on one of said plate members comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels, the finger pattern potions of each of said sets of electrodes being interdigitated with each other,

an electron source,

a target member,

said electron source and target members being positioned along opposite edges of said plate members with said electrodes therebetween,

means for accelerating the flow of electrons between said electron source and said target, the electrons passing between the surfaces of said plate members, and

means ,for selectively applying a potential between preselected ones of said paired electrodes on said one of said plate members and the opposing electrode means on the other of said plate members to provide a transverse electric field to prevent the flow of electrons between said electron source and said target in the channels encompassed thereby, whereby electrons flow to said target in the channels having no transverse electric field thereacross.

9. The scanner of claim 8 wherein the electrode means on the other of said plate members comprises a single electrode covering substantially the entire broad surface thereof.

10. The scanner of claim 8 wherein the electrode means on the other of said plate members comprises a plurality of separate electrodes arranged in parallel rows opposite said paired electrodes, said accelerating means comprising means for establishing a potential gradient running from electrode to electrode between the cathode and target on both of said plate members.

11. The scanner of claim 8 wherein the electrode means covers substantially all of the surface area of said plate members between which the channels are formed.

12. The scanner of claim 8 wherein said sets of paired electrodes are arranged in succession in substantially parallel rows.

13. The scanner of claim 1 wherein said channels are further defined by grooves formed in the surface of at least one of said plate members.

14. The scanner of claim 13 wherein the grooves are formed in the surface of the other of said plate members, the electrode means of the other of said plate members comprising conductive strips in said grooves.

15. The scanner of claim 8 wherein said means for accelerating the flow of electrons between said electron source and said target member comprises an accelerating electrode positioned proximate to said source and means for providing a potential between said accelerating electrode and said source.

16. The scanner of claim 8 wherein said positioning means is adapted to separate the plate members from each other to form a narrow slot between the surfaces thereof, the channels being formed in said slot.

17. An electron beam line scanner comprising:

a pair of plate members of a dielectric material,

an electron source,

a target,

control electrode means on one surface of each of said platemembers for controlling the electron flow between said electron source and said target,

means for positioning said plate members with the electrode means of one in opposing relationship and in close proximity to the electrode means of the other, electron paths between the electron source and target being formed between said plate members,

the electrode means on one of said plate members comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels between the electron source and target, the finger pattern portions of each of said sets of electrodes being interdigitated with each other, said electrodes being arranged in successive rows,

the electrode means on the other of said plate members comprising a single electrode covering substantially the entire surface thereof,-

s'aid electrodes covering substantially all of the surface areas of said plate members between which the channels are formed,

means for accelerating the flow of electrons between said electron source and said target, the electrons flowing between said opposing electrode means,

and

means for selectively applying a potential between preselected ones of said paired electrodes on said one of said plate members and an opposing electrode on the other of said plate members to provide a transverse electric field to prevent the flow of electrons between said electron source and said target in the channels encompassed thereby, whereby electrons flow to said target in the channels having no transverse electric field thereacross.

18. The scanner of claim 17 wherein the means for accelerating the flow of electrons between said source and target comprises an accelerator electrode positioned on said one of said plate members between said source and said paired electrodes, and means for applying an electron accelerating potential to said accelerator electrode.

19. The scanner of claim 18 and further including a modulator electrode positioned on said one of said plate members and means for providing a modulation signal to said modulator electrode.

20. The scanner of claim 19 wherein said modulator and accelerator electrodes are positioned along opposite edges of said one of said plate members, said modulator and accelerator electrodes extending over the opposite end portions of said plate member.

Claims

1. In an electron beam line scanner, an electron source, a target and means for accelerating the flow of electrons between said electron source and target to form an electron beam therebetween, the improvement including means for causing said beam to scan said target in response to a digital addressing signal, comprising: a pair of plate members, said plate members being positioned between the electron source and target with one of each of their broad surfaces opposite each other, said beam passing between said surfaces on a path substantially parallel thereto, control electrode means on each of said opposite broad surfaces, said electrode means being positioned opposite each other, said control electrode means comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels running between the cathode and targEt, the finger pattern portions of the electrodes of each of said sets of electrodes being interdigitated with each other, and non-coded electrode means positioned opposite each of said sets of paired electrodes, and means for applying potentials between pre-selected ones of said finger pattern electrodes and said non-coded electrode means to provide transverse electric fields across selected ones of said channels, thereby preventing the flow of electrons in said selected channels, the electron flow being permitted in those channels having no transverse electric fields thereacross.

8. A electron beam line scanner comprising: a pair of plate members, control electrode means on one surface of each of said plate members, means for positioning said plate members with the electrode means of one in opposing relationship and in close proximity to the electrode means of the other, the electrode means on one of said plate members comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels, the finger pattern potions of each of said sets of electrodes being interdigitated with each other, an electron source, a target member, said electron source and target members being positioned along opposite edges of said plate members with said electrodes therebetween, means for accelerating the flow of electrons between said electron source and said target, the electrons passing between the surfaces of said plate members, and means for selectively applying a potential between preselected ones of said paired electrodes on said one of said plate members and the opposing electrode means on the other of said plate members to provide a transverse electric field to prevent the flow of electrons between said electron source and said target in the channels encompassed thereby, whereby electrons flow to said target in the channels having no transverse electric field thereacross.

17. An electron beam line scanner comprising: a pair of plate members of a dielectric material, an electron source, a target, control electrode means on one surface of each of said plate members for controlling the electron flow between said electron source and said target, means for positioning said plate members with the electrode means of one in opposing relationship and in close proximity to the electrode means of the other, electron paths between the electron source and target being formed between said plate members, the electrode means on one of said plate members comprising a plurality of sets of paired electrodes having finger portions arranged in a coded finger pattern to define a plurality of electron channels between the electron source and target, the finger pattern portions of each of said sets of electrodes being interdigitated with each other, said electrodes being arranged in successive rows, the electrode means on the other of said plate members comprising a single electrode covering substantially the entire surface thereof, said electrodes covering substantially all of the surface areas of said plate members between which the channels are formed, said electron source and target members being positioned along opposite edges of said plate members with said electrodes therebetween, means for accelerating the flow of electrons between said electron source and said target, the electrons flowing between said opposing electrode means, and means for selectively applying a potential between preselected ones of said paired electrodes on said one of said plate members and an opposing electrode on the other of said plate members to provide a transverse electric field to prevent the flow of electrons between said electron source and said target in the channels encompassed thereby, whereby electrons flow to said target in the channels having no transverse electric field thereacross.